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1.1 root 1: /*
2: * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3: *
4: * @APPLE_LICENSE_HEADER_START@
5: *
6: * The contents of this file constitute Original Code as defined in and
7: * are subject to the Apple Public Source License Version 1.1 (the
8: * "License"). You may not use this file except in compliance with the
9: * License. Please obtain a copy of the License at
10: * http://www.apple.com/publicsource and read it before using this file.
11: *
12: * This Original Code and all software distributed under the License are
13: * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
14: * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
15: * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
16: * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT. Please see the
17: * License for the specific language governing rights and limitations
18: * under the License.
19: *
20: * @APPLE_LICENSE_HEADER_END@
21: */
22: /*
23: * Copyright (c) 1982, 1992, 1993
24: * The Regents of the University of California. All rights reserved.
25: *
26: * Redistribution and use in source and binary forms, with or without
27: * modification, are permitted provided that the following conditions
28: * are met:
29: * 1. Redistributions of source code must retain the above copyright
30: * notice, this list of conditions and the following disclaimer.
31: * 2. Redistributions in binary form must reproduce the above copyright
32: * notice, this list of conditions and the following disclaimer in the
33: * documentation and/or other materials provided with the distribution.
34: * 3. All advertising materials mentioning features or use of this software
35: * must display the following acknowledgement:
36: * This product includes software developed by the University of
37: * California, Berkeley and its contributors.
38: * 4. Neither the name of the University nor the names of its contributors
39: * may be used to endorse or promote products derived from this software
40: * without specific prior written permission.
41: *
42: * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
43: * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
44: * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
45: * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
46: * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
47: * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
48: * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
49: * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
50: * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
51: * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
52: * SUCH DAMAGE.
53: *
54: * @(#)ns_cksum.c 8.1 (Berkeley) 6/10/93
55: */
56:
57: #include <sys/param.h>
58: #include <sys/mbuf.h>
59:
60: /*
61: * Checksum routine for Network Systems Protocol Packets (Big-Endian).
62: *
63: * This routine is very heavily used in the network
64: * code and should be modified for each CPU to be as fast as possible.
65: */
66:
67: #define ADDCARRY(x) { if ((x) > 65535) (x) -= 65535; }
68: #define FOLD(x) {l_util.l = (x); (x) = l_util.s[0] + l_util.s[1]; ADDCARRY(x);}
69:
70: u_short
71: ns_cksum(m, len)
72: register struct mbuf *m;
73: register int len;
74: {
75: register u_short *w;
76: register int sum = 0;
77: register int mlen = 0;
78: register int sum2;
79:
80: union {
81: u_short s[2];
82: long l;
83: } l_util;
84:
85: for (;m && len; m = m->m_next) {
86: if (m->m_len == 0)
87: continue;
88: /*
89: * Each trip around loop adds in
90: * word from one mbuf segment.
91: */
92: w = mtod(m, u_short *);
93: if (mlen == -1) {
94: /*
95: * There is a byte left from the last segment;
96: * ones-complement add it into the checksum.
97: */
98: #if BYTE_ORDER == BIG_ENDIAN
99: sum += *(u_char *)w;
100: #else
101: sum += *(u_char *)w << 8;
102: #endif
103: sum += sum;
104: w = (u_short *)(1 + (char *)w);
105: mlen = m->m_len - 1;
106: len--;
107: FOLD(sum);
108: } else
109: mlen = m->m_len;
110: if (len < mlen)
111: mlen = len;
112: len -= mlen;
113: /*
114: * We can do a 16 bit ones complement sum using
115: * 32 bit arithmetic registers for adding,
116: * with carries from the low added
117: * into the high (by normal carry-chaining)
118: * so long as we fold back before 16 carries have occured.
119: */
120: if (1 & (int) w)
121: goto uuuuglyy;
122: #ifndef TINY
123: /* -DTINY reduces the size from 1250 to 550, but slows it down by 22% */
124: while ((mlen -= 32) >= 0) {
125: sum += w[0]; sum += sum; sum += w[1]; sum += sum;
126: sum += w[2]; sum += sum; sum += w[3]; sum += sum;
127: sum += w[4]; sum += sum; sum += w[5]; sum += sum;
128: sum += w[6]; sum += sum; sum += w[7]; sum += sum;
129: FOLD(sum);
130: sum += w[8]; sum += sum; sum += w[9]; sum += sum;
131: sum += w[10]; sum += sum; sum += w[11]; sum += sum;
132: sum += w[12]; sum += sum; sum += w[13]; sum += sum;
133: sum += w[14]; sum += sum; sum += w[15]; sum += sum;
134: FOLD(sum);
135: w += 16;
136: }
137: mlen += 32;
138: #endif
139: while ((mlen -= 8) >= 0) {
140: sum += w[0]; sum += sum; sum += w[1]; sum += sum;
141: sum += w[2]; sum += sum; sum += w[3]; sum += sum;
142: FOLD(sum);
143: w += 4;
144: }
145: mlen += 8;
146: while ((mlen -= 2) >= 0) {
147: sum += *w++; sum += sum;
148: }
149: goto commoncase;
150: uuuuglyy:
151: #if BYTE_ORDER == BIG_ENDIAN
152: #define ww(n) (((u_char *)w)[n + n + 1])
153: #define vv(n) (((u_char *)w)[n + n])
154: #else
155: #if BYTE_ORDER == LITTLE_ENDIAN
156: #define vv(n) (((u_char *)w)[n + n + 1])
157: #define ww(n) (((u_char *)w)[n + n])
158: #endif
159: #endif
160: sum2 = 0;
161: #ifndef TINY
162: while ((mlen -= 32) >= 0) {
163: sum += ww(0); sum += sum; sum += ww(1); sum += sum;
164: sum += ww(2); sum += sum; sum += ww(3); sum += sum;
165: sum += ww(4); sum += sum; sum += ww(5); sum += sum;
166: sum += ww(6); sum += sum; sum += ww(7); sum += sum;
167: FOLD(sum);
168: sum += ww(8); sum += sum; sum += ww(9); sum += sum;
169: sum += ww(10); sum += sum; sum += ww(11); sum += sum;
170: sum += ww(12); sum += sum; sum += ww(13); sum += sum;
171: sum += ww(14); sum += sum; sum += ww(15); sum += sum;
172: FOLD(sum);
173: sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
174: sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
175: sum2 += vv(4); sum2 += sum2; sum2 += vv(5); sum2 += sum2;
176: sum2 += vv(6); sum2 += sum2; sum2 += vv(7); sum2 += sum2;
177: FOLD(sum2);
178: sum2 += vv(8); sum2 += sum2; sum2 += vv(9); sum2 += sum2;
179: sum2 += vv(10); sum2 += sum2; sum2 += vv(11); sum2 += sum2;
180: sum2 += vv(12); sum2 += sum2; sum2 += vv(13); sum2 += sum2;
181: sum2 += vv(14); sum2 += sum2; sum2 += vv(15); sum2 += sum2;
182: FOLD(sum2);
183: w += 16;
184: }
185: mlen += 32;
186: #endif
187: while ((mlen -= 8) >= 0) {
188: sum += ww(0); sum += sum; sum += ww(1); sum += sum;
189: sum += ww(2); sum += sum; sum += ww(3); sum += sum;
190: FOLD(sum);
191: sum2 += vv(0); sum2 += sum2; sum2 += vv(1); sum2 += sum2;
192: sum2 += vv(2); sum2 += sum2; sum2 += vv(3); sum2 += sum2;
193: FOLD(sum2);
194: w += 4;
195: }
196: mlen += 8;
197: while ((mlen -= 2) >= 0) {
198: sum += ww(0); sum += sum;
199: sum2 += vv(0); sum2 += sum2;
200: w++;
201: }
202: sum += (sum2 << 8);
203: commoncase:
204: if (mlen == -1) {
205: #if BYTE_ORDER == BIG_ENDIAN
206: sum += *(u_char *)w << 8;
207: #else
208: sum += *(u_char *)w;
209: #endif
210: }
211: FOLD(sum);
212: }
213: if (mlen == -1) {
214: /* We had an odd number of bytes to sum; assume a garbage
215: byte of zero and clean up */
216: sum += sum;
217: FOLD(sum);
218: }
219: /*
220: * sum has already been kept to low sixteen bits.
221: * just examine result and exit.
222: */
223: if(sum==0xffff) sum = 0;
224: return (sum);
225: }
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